I've been chasing an rpm-dependant ticking sound coming from the engine compartment on my '07 STS V8. It is most noticeable at about 1200rpm, just above idle. It sounds like diesel clatter. I have listened from above the motor, and it's below that. I have listened from underneath the motor, and it's above that. It's not an exhaust leak.

I have seen several threads describing the same issue with no resolution and dealerships labeling it as "normal." I have had several other Northstar cars and haven't heard this type of sound and I don't consider it to be normal.

I'm wondering if it is a sound that is supposed to be masked by an insulation barrier -- the Fuel Injection Sight Shield (engine cover) is in place. However, there is a piece of insulation directly behind the cover that I've circled below. On my car the piece of insulation was in place, but seems to be offset to the left. I'm wondering if this is out of place.

The problem is that I can't find that insulation piece on any parts diagram. I've circled it in the picture below.

a) what is this part called/is there a part number/ could this being out of place allow the ticking sound into the cabin.

b) what are the other options that would cause such a sound? Is the purge valve something that could be an issue on this car (I know it's primarily a V6 problem, but these cars do have purge valves, too).

Search would show that noise is a common "problem". I quote it as its not a problem and perfectly normal. You have a 4.6 N* V8 with VVT. The variable valve timing will cause this engine to chatter like a cammed LS1. Make sure you have a GOOD oil filter with an anti drain back valve (Mobil k&n wix etc) maintain proper oil level with 5or10w30 synthetic ONLY and beat the piss out of it every so often to reduce carbon deposits.

My car has always done this. Looking at your picture, that sound insulation seems to be in the correct place. You can see that the contours line up perfectly with the engine sight shield. I'm not convinced you actually have a problem here.

Not all Northstars are the same. I have a Northstar in my Bonneville and it doesn't make this noise but it's also not VVT along with other differences.

Search would show that noise is a common "problem". I quote it as its not a problem and perfectly normal. You have a 4.6 N* V8 with VVT. The variable valve timing will cause this engine to chatter like a cammed LS1. Make sure you have a GOOD oil filter with an anti drain back valve (Mobil k&n wix etc) maintain proper oil level with 5or10w30 synthetic ONLY and beat the piss out of it every so often to reduce carbon deposits.

"Search would show" is a bit condescending. The first post made it clear that I have already searched. I've had several Northstar motors before and nothing has clattered like a damned diesel with a racket that bounces off of the wall when I'm going through a drive-through.

The fact that other people have the noise, while others don't, begs the question -- what exactly is making the noise and why.

Originally Posted by ddalder

My car has always done this. Looking at your picture, that sound insulation seems to be in the correct place. You can see that the contours line up perfectly with the engine sight shield. I'm not convinced you actually have a problem here.

That's not a picture of my car, I just circled the part I'm trying to find and cannot find it in any of the GM parts suppliers' web sites.

"Search would show" is a bit condescending. The first post made it clear that I have already searched. I've had several Northstar motors before and nothing has clattered like a damned diesel with a racket that bounces off of the wall when I'm going through a drive-through.

The fact that other people have the noise, while others don't, begs the question -- what exactly is making the noise and why.

That's not a picture of my car, I just circled the part I'm trying to find and cannot find it in any of the GM parts suppliers' web sites.

Still looking for that part number...

I already told you what makes the noise its the VVT. Older northstars didn't have VVT, that was only on the LC3 and LH2. Ever LH2 I've heard has the noise. Running lower octane fuel or motors with carbon makes it worse so people who are cheap tend to hear it more.

I really don't know what you think you're "proving." Both of those threads were people that had (probably a very similar) noise. NEITHER of those threads established a definitive cause (and I've read both of them before).

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in the PI.

Condition/Concern:

Some 04 Cadillac SRX, XLR 4.6L (LH2) Northstar engines may experience a cold start, loud ratcheting type/ clicking type noise that lasts 1 -2 seconds. The noise will be heard from the front of the engine. The vehicle usually has to set for a minimum of 1-2 hours sometimes up to an 8-hour soak is necessary to reproduce the noise. ( the oil has to drain out of the phaser to duplicate this condition)

To check for the cause of the cold start, loud ratcheting type/ clicking type noise concern:

Remove both camshaft covers (no specific engine soak time is required as the oil pressure will drained off during the time to remove both camshaft covers).
Using an open-end wrench on each of the four camshafts try to rotate the camshaft in both a clockwise and counter clockwise direction. Slight rotation (less that 3 degrees) will occur due to slack in the drive chains.
If any of the camshafts rotate up to approximately 25 degrees, the locking pin on that cam phaser is not engaging. This non-locking cam phaser should be replaced.
Cam Phaser Part numbers are:

LH Exhaust - 12567415

LH Intake - 12567417

RH Exhaust - 12567414

RH Intake - 12567416

Note At this time do not remove the phaser bolt from the phaser, keep the phaser together and put it in a plastic bag to contain the sediment. The phaser is required to be shipped back to the WPC.

If none of the four camshafts rotate in either direction it's possible that some sediment was disrupting the locking pin and now it has been dislodged. The camshaft covers should be reinstalled and the noise concern should be reevaluated.
The camshaft covers gasket p/n if necessary is 12576394 and 12576395.

Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance. This diagnostic approach was developed for the vehicle with the VIN you entered and should not automatically be used for other vehicles with similar symptoms.

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Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

Note that tsb ONLY applies to the 04 LH2. All four of my cam actuators have been replaced due to oil seal issues and my engine still makes the NORMAL noise you are complaint about. I'm not going to waste my time arguing with you and explaining how the VVT functions you can spend all night browsing the Internet to find out that even BMWs with VVT has the same normal noise as its a function of the VVT.

Bmoore, what those links would tell me is that I'm not the only one with this condition. It tells me that if the condition is that prevalent, it's probably normal. It tells me that one without the condition would actually be out of the ordinary.

Look at it this way. Your previous northstars that didn't have vvt. If you had that noise and you brought it up on the forums and nobody, or one or two people said they have the same issue, while a majority said they didn't, you'd know there's something up.

Flip flop it. I know we're trained to think that if there is some kind of "abnormal" noise, there's something wrong. But in this case, based on the members surveyed on here, the noise is normal.

Send a private message to Chris at rippy Cadillac. His name on the forums is "rippypartsdept." Include that picture where you circle the part in question or include a link to this thread and see if he can get you a part number.

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By the way, I owned 3 fwd northstar cars. No noise. I owned a 2007 STS V8. Noise. I wouldn't be too concerned.

My 2006 V8 STS Northstar sounds like a '49 Olds with a worn out valve train. It's normal. Learn to love the car or get rid of it because you're not going to fix it. I'm amazed that you haven't found some dirt floor shop that wants to take it all apart for you looking for nothing.